A large number of samples can be injected at high pressure into a chromatographic column in a system that uses an injector valve. At the start of a cycle, the tip of a probe is moved into a sample well to withdraw a sample, and then to a wash station to wash the probe tip. The probe tip then moves against a dock and high pressure mobile phase fluid moves from a pump through the valve and through a sample loop that includes the probe and dock in series, and again through the valve to the column. Prior to loading the probe with a sample, the valve connects the pump to the column to continually pass mobile phase fluid through the column. To draw a sample into the probe, a metering syringe is connected through the valve to the probe. For probe washing, a rinse syringe is connected to a rinse nozzle to supply pressured fluid thereto, while occasionally fluid from a reservoir reloads the rinse syringe. In addition, rinsing fluid sprayed by the nozzle into a cup to wash the probe tip, is drained to a waste syringe. Furthermore, the metering syringe is connected directly to the mobile phase pump, as required (typically at the start of the days work) so as to remove gas bubbles. It can be appreciated that in such a system a large number of items are used, and there are a large number of tubes and means for interconnecting the tubes at different times in the cycle.
A prior injection valve performs many of the functions required, but with the addition of a cleaning nozzle and associated equipment additional switching of flow is required. It would be possible to add another valve similar to a prior injection valve to perform switching for the rinsing functions, but this would add cost and size, and reduce reliability. Modem laboratories have limited bench space, and they demand extremely high system reliability, even while placing a high premium on economy. A single valve that could automatically connect the proper tubes at the proper times in the cycle would reduce cost and size, and would increase reliability. However, present injection valves such as shown in U.S. Pat. No. 4,242,909 include a single circle of holes and a single rotor with channels that connect pairs of holes. Pivoting of the channel to a different position connects all channels to different pairs of holes. It is difficult to construct such a valve to perform all functions of injection and cleaning so the proper connections are made at every time during a sampling cycle.